Mongodb C# - Registering class maps with generics works, where using types fails-CodePudding

I have a collection of objects, and each object has a property, EventData, that is many different types. These types all inherit from an IEventData interface.

For example:

{ _id: '...', EventData: { _t: 'TypeA', ... } }
{ _id: '...', EventData: { _t: 'TypeB', ... } }

I'm currently facing an issue with the MongoDB C# driver when trying to register class maps. When using the generic version to register the class map, the EventData object is correctly serialised with all properties and the type discriminator:

BsonClassMap.RegisterClassMap<TypeA>();
// Full event data is written to collection
// { _id: '...', EventData: { _t: 'TypeA', InterfaceProperty: '...', ClassProperty: '...' } }

This works fine, however I have a large amount of different event types, and want to try and use some reflection to help automate this. When trying to use the non-generic version of the RegisterClassMap whilst iterating over all types that implement the IEventData interface, only the interface members are serialised:

var types = AppDomain.CurrentDomain.GetAssemblies()
.SelectMany(i => i.GetTypes())
.Where(t => typeof(IEventData).IsAssignableFrom(t));

foreach (var type in types)
{
    // If it's an interface, skip as we can't register those
    if (type.IsInterface)
        continue;
        
    if (!BsonClassMap.IsClassMapRegistered(type))
       BsonClassMap.RegisterClassMap(new BsonClassMap(type));
        
 }

// Only the interface properties are written to collection
// { _id: '...', EventData: { _t: 'TypeA', InterfaceProperty: '...' } }

Is there some property or something I'm missing to set when using the non-generic type to register the class maps that allow the full type to stored in the collection?

Thanks Justin

CodePudding user response：

The difference between the two variants is that in case of RegisterClassMap<T>() a call to AutoMap is included. In order to harmonize your reflection based approach with the call of the generic version, you can add the call to AutoMap:

var cm = new BsonClassMap(type);
cm.AutoMap();
BsonClassMap.RegisterClassMap(cm);